In conventional compressors and refrigeration cycle devices using same, there is a tendency that HFC (hydrofluorocarbon)-based refrigerant (HFC-based refrigerant, hereinafter) having zero ozone depletion potential is used as a working refrigerant. However, since this HFC-based refrigerant has extremely high global warming potential (GWP, hereinafter), the HFC-based refrigerant is acknowledged as a problem in recent years in terms of protection of the global environment. Hence, a refrigerant which is mainly composed of hydrofluoroolefin having double bond between carbons of low GWP is now under review.
A compressor and a refrigeration cycle device using a conventional HFC-based refrigerant will be described with reference to FIGS. 6 to 8 (see patent documents 1 and 2 for example).
FIG. 6 is a vertical sectional view of a rotary compressor using the conventional HFC-based refrigerant.
A stator 2a of a motor 2 is fixed to an upper portion in a container 1, a compressing mechanism 5 including a shaft 4 driven by a rotor 2b is fixed to a lower portion in the container 1. A main bearing 7 is fixed to an upper end of a cylinder 6 of a compressing mechanism 5 through a bolt, and an auxiliary bearing 8 is fixed to a lower end of the cylinder 6 through a bolt. In the cylinder 6, a piston 9 is inserted into an eccentric portion 4a of the shaft 4, and the piston 9 is eccentrically rotated.
In the container 1, R410A (mixture of HFC32 and HFC125) is charged as a refrigerant, and refrigeration oil 3 composed of polyol ester having compatibility with the refrigerant is accumulated in a bottom of the container 1.
FIG. 7 is a transverse sectional view of the rotary compressor using the conventional HFC-based refrigerant. The piston 9 is inserted into an inner surface of the cylinder 6, the piston 9 rotates together with rotation of the shaft 4, and a refrigerant is sucked and compressed in a suction chamber 13 and a compression chamber 14 which is partitioned by a vane 10.
Action and operation of the rotary compressor having the above-described configuration will be described below.
First, a refrigerant is sucked from a suction port 12 formed in the cylinder 6 into the suction chamber 13. A refrigerant in the compression chamber 14 is compressed as the piston 9 rotates in a left-handed direction (direction of arrow), and the refrigerant is discharged into the container 1 from a discharge port (not shown) through a discharge notch 15. The compressed refrigerant discharged into the container 1 passes through a gap of the motor 2, and the refrigerant is discharged from a discharge pipe 16 provided on an upper portion of the container 1. At that time, mist of the refrigeration oil is also discharged together.
Due to a configuration of the rotary compressing mechanism, a portion thereof which Due to a configuration is a contact portion between a tip end of the vane 10 and an outer periphery of the piston 9. High discharge pressure is applied to a back portion 10b of the vane 10 in addition to a vane spring 11, and a large force caused by differential pressure with respect to pressure in the cylinder acts. Therefore, a contact state between the tip end 10a of the vane 10 and the outer periphery of the piston 9 becomes boundary lubrication and this portion is under a high temperature severe environment condition. Hence, as disclosed in patent document 2, the vane 10 is subjected to nitriding treatment, and a surface of the vane 10 is plated with CrN (chromium nitride) ion or TiN (titanium nitride) ion, thereby enhancing wear resistance to secure reliability.
Next, a basic refrigeration cycle device in which a rotary compressor 20 which sucks, compresses and discharges the HFC-based refrigerant described in patent document 2 is disposed will be described with reference to FIG. 8.
As shown in FIG. 8, the rotary compressor 20 compresses low temperature and low pressure refrigerant gas, discharges high temperature and high pressure refrigerant gas and sends the refrigerant gas to a condenser 21. The HFC-based refrigerant gas sent to the condenser 21 becomes high temperature and high pressure refrigerant liquid while discharging its heat into air, and is sent to an expansion mechanism 22 (e.g., expansion valve or capillary tube). The high temperature and high pressure refrigerant liquid which passes through the expansion mechanism 22 becomes low temperature and low pressure moisture vapor by a throttle effect, and is sent to an evaporator 23. The refrigerant which enters the evaporator 23 absorbs heat from its periphery, and low temperature and low pressure refrigerant gas which comes out from the evaporator 23 is sucked into the rotary compressor 20, and the same cycle is repeated thereafter.